Treatment of choice for medullary carcinoma of thyroid is:
**Core Concept**
Medullary carcinoma of the thyroid is a type of neuroendocrine tumor originating from the parafollicular cells (C cells) of the thyroid gland. The treatment of choice for medullary carcinoma of the thyroid involves surgical resection, followed by targeted therapy.
**Why the Correct Answer is Right**
The treatment of choice for medullary carcinoma of the thyroid is surgical resection, specifically a total thyroidectomy, to remove the tumor and prevent recurrence. This is followed by targeted therapy with tyrosine kinase inhibitors (TKIs) such as vandetanib or cabozantinib, which inhibit the RET and MET signaling pathways that are often overexpressed in medullary thyroid carcinoma. These TKIs have been shown to improve progression-free survival and overall survival in patients with advanced disease.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because radioactive iodine therapy is not effective in medullary thyroid carcinoma, as these tumors do not take up iodine.
**Option B:** This option is incorrect because chemotherapy is not the primary treatment for medullary thyroid carcinoma, although it may be used in advanced cases.
**Option C:** This option is incorrect because external beam radiation therapy is not a standard treatment for medullary thyroid carcinoma.
**Clinical Pearl / High-Yield Fact**
Medullary thyroid carcinoma often presents with calcitonin elevation, which can be used as a tumor marker for diagnosis and follow-up.
**Correct Answer: C. Total thyroidectomy with targeted therapy.**